Many processes are known for the conversion of nongaseous carbonaceous material into gaseous, liquid and solid products. For example, nongaseous carbonaceous material may be converted by carbonization at temperatures above 900.degree. F. Pyrolysis of nongaseous carbonaceous material in an entrained bed reactor, or transport reactor, has the advantage of limiting the pyrolysis to short residence times. Short residence times enhances the quality and/or yield of gaseous and liquid products which tend to decompose under longer residence times carbonization processes.
Carbonization at short residence times, often referred to as flash pyrolysis or simply pyrolysis, requires rapid heating of the nongaseous carbonaceous material. One method used in pyrolysis to achieve rapid heating is to simultaneously introduce with the nongaseous carbonaceous material a heat-supplying medium, or heating medium, to the pyrolysis zone which becomes intimately mixed with the fresh nongaseous carbonaceous material. Since most pyrolysis processes also produce a solid product, or carbonaceous residue, or char, or coke, it is economical to utilize the solid product as the heat-supplying medium.
The solid product can be heated in a heating zone or zones to a temperature greater than the pyrolysis temperature and recycled to the pyrolysis zone as the heating medium. The solid product can be heated in the heating zone, or reaction zone, by partial oxidation. Partial oxidation consumes a portion of the solid product and produces a gaseous product and thermal energy which is transferred in part to the residual solid product. The gaseous product produced contains carbon dioxide and often gaseous H.sub.2 O and carbon monoxide. The gaseous product if not immediately separated from the solid product, or nongaseous carbonaceous material, will react with the solid product and produce additional carbon monoxide. Carbon monoxide formation reactions are endothermic and tend to remove sensible heat from the system and are therefore to be avoided if possible.
In many processes, however, it is necessary to transport the solid product, or char, or nongaseous carbonaceous material to the heating zone. Often the transport line is also used as a first stage heating zone. When the transport line is used as a heating zone there is frequently substantial carbon monoxide present with the stream as it enters the second stage heating zone.
The invention is useful especially when applied to the second stage heating zone. The invention is an apparatus and method to produce additional heating of the nongaseous carbonaceous material by oxidation of at least a portion of the carbon monoxide introduced to the heating zone to carbon dioxide and transferring the thermal energy released by oxidation reaction at least in part to the nongaseous carbonaceous material thereby increasing the temperature thereof and thereby producing a heat-supplying medium.
More specifically, pyrolysis processes are used to convert particulate carbonaceous material such as coal, either coking or noncoking coal, or agglomerative or nonagglomerative coal, to a valuable gaseous product and char product. The gaseous product can be cooled to produce a valuable liquid product. The char product can be heated separately by partial oxidation to raise the residual char to a higher temperature. The heated char can then be recycled to the pyrolysis zone to supply at least a portion of the heat required for pyrolysis.
Other pyrolysis processes, which utilize heated solid product as a heat-supplying medium are processes for the pyrolysis of waste materials, such as municipal solid waste and industrial solid waste.
This invention is useful in processes for heating a nongaseous carbonaceous material to a higher temperature so that it can be utilized as a heat supplying medium. This invention is also useful in processes for pyrolyzing nongaseous carbonaceous material in a pyrolysis zone, separating the solid product or char from the gaseous product, heating the char in a heating zone to a temperature sufficiently high to produce a heat-supplying medium, and recycling the heat-supplying medium to pyrolysis zone to supply heat thereto.